(1) Field of the Invention
The present invention relates to a process and a fixture for ascertaining pressure losses in a pressure line, in particular in a gas or heating oil line assigned to a tunnel furnace or anode furnace, in which one or more consumers are connected to the line, the medium is held enclosed within the pressure line under operating pressure for a selectable period of time and the enclosed operating pressure acts on a pressure watchdog by means of which a drop in pressure can be detected.
(2) Description of the Prior Art
A process and a fixture of prior art for application of this process are familiar from DE-19 529 362 A1. The pressure watchdog connected to the pressure line does indeed provide a reliable means of detecting a drop in pressure caused by a leak; however, there is no provision for automatic reaction according to the operating status of the pressure watchdog in this case. This means a system can only be shut off with a time lag, the result of this being that even when a leak is detected, a significant volume of fuel and thus a hazardous medium can emerge.
The purpose of the present invention is therefore to improve the process and the fixture of the aforementioned type in such a way that, although only a very minor scope of circuitry is required, the pressure line can be checked at any time or at selectable time intervals and that, depending on the measuring result, the supply to the consumers can be resumed or the pressure line deactivated. The construction work required to achieve this is intended to be kept to a small extent whilst still guaranteeing an exact measuring result.
In accordance with the present invention, the process for ascertaining pressure losses in a pressure line is characterised in that the shut-off pressure line connected to the pressure watchdog has an adjustable quantity of the enclosed medium supplied to it during a particular period of time, that the operating characteristics of the pressure watchdog are monitored during the supply of medium and that the pressure line is enabled or blocked depending on the operating position of the pressure watchdog.
It is advantageous in this case for the operating pressure of the pressure line to be reduced to the switching point of the pressure watchdog by means of the consumers prior to the supply of medium into the pressure line and for the supply of medium into the pressure line to be set using a timer switch assigned to a shut-off valve, in which case the unit of time during which the pressure line is blocked is set by one or more shut-off valves inserted in the pressure line and controlled by a time interval switch.
Furthermore, it is appropriate for the pressure watchdog connected to the pressure line to actuate a limit value switch by means of which the switching valves allocated to the consumers are controlled directly or via a governor in accordance with the operating position of the pressure watchdog.
The fixture for applying this process is characterised in that the blocked pressure line connected to the pressure watchdog can have an adjustable volume of the enclosed medium supplied to it via a branch line within a unit of time, and that the pressure watchdog is connected to a circuit by means of which the pressure line can be controlled depending on the operating status of the pressure watchdog.
In order to supply the medium into the pressure line which is blocked for a unit of time which can be selected using a time interval switch, it is advantageous for the shut-off valve adjacent to the pressure watchdog to be provided with a bypass line as a branch line, with this line being opened in a controlled fashion and connected to the pressure line or a line through which the medium is routed, and to unblock the bypass line using a timer switch. In addition, it should be possible to connect the pressure watchdog to a limit value switch by means of which the pressure line can be opened or blocked, depending on the operating status of the pressure watchdog.
If a pressure line is tested using the process described in accordance with the present invention or is equipped with a fixture for applying this process in accordance with the present invention, then it is an easy and quick matter to establish a drop in pressure in the pressure line and to react accordingly. This is namely because the pressure watchdog is reduced to its switching point by the consumers and if it does not then rise above the nominal switching point due to the supply of medium into the pressure line when the line is blocked, then this is a sign that there is an abnormal leakage present, leaks on the shut-off valves of the consumers and/or irregularities in the pulse control system. In such an eventuality, the tested portion of the pressure line must be switched off; in contrast, operation can be resumed immediately if no leakage or no other malfunction is found. Thus, with little complexity and within a short space of time, it is possible to undertake an automatic and reliable test, thereby increasing the levels of safety when working with flammable media.